intakes
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intakes
what would be the advantages or disadvantages of a dual port intake from Offenhauser as apposed to their single port intake. The single intake is cheaper. Any suggestion. Which would be better on Gas?
Thanx
Thanx
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From: Lima, OH
intakes
Do you mean port or plane? If you mean plane, a dual plane would be better for the 4.9L. Single plane manifolds are designed more for racing engines and high RPM use and require the faster intake velocity of high revving to make them effective. A single plane is more aimed at normal street engines operating under about 6000RPM.
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TrailDawg
https://www.ford-trucks.com/dcforum/User_files/3aaa4bac6f539876.jpg
1993 F150 2WD
6" Lift w/35's
Auburn Pro-Series Diff. w/4.30 gears
http://www.geocities.com/ProjectTrailDawg
Post Fiend
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intakes
I assume you are talking carburated 300 I6s. But I always wondered what is inside the plenum on the EFI 300. I assume it is one big box, but if it were divided between the two throttle body barrels (can we call them barrels when it is not a carburator?) then we would have a dual plane intake--right? Or is dual/single plane not relavant for EFI?
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From: Lima, OH
intakes
I got this out of a *cough*Mopar*cough* book I had laying around.
"For most street/strip applications, a dual plain intake will offer the best performance. It's lower plenum height and shorter runner lengths provide for a higher intake velocity which improves bottom end torque. Single plain manifolds are reserved racing engines who's normal operation is above 5000 RPM. This type of manifold usually has a very tall plenum and long, large runners to provide more air/fuel at higher engine speeds."
TrailDawg
https://www.ford-trucks.com/dcforum/User_files/3aaa4bac6f539876.jpg
1993 F150 2WD
6" Lift w/35's
Auburn Pro-Series Diff. w/4.30 gears
http://www.geocities.com/ProjectTrailDawg
"For most street/strip applications, a dual plain intake will offer the best performance. It's lower plenum height and shorter runner lengths provide for a higher intake velocity which improves bottom end torque. Single plain manifolds are reserved racing engines who's normal operation is above 5000 RPM. This type of manifold usually has a very tall plenum and long, large runners to provide more air/fuel at higher engine speeds."
TrailDawg
https://www.ford-trucks.com/dcforum/User_files/3aaa4bac6f539876.jpg
1993 F150 2WD
6" Lift w/35's
Auburn Pro-Series Diff. w/4.30 gears
http://www.geocities.com/ProjectTrailDawg
Posting Guru
Joined: Dec 1999
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From: Copley, OH
intakes
This came up recently on the Ford Six Performance board.
IIRC the 300 EFI manifold has a divider in the plenum with a notch to allow some bleed from side to side. Very similar in concept and effect to some dual plane carb manifolds with a notch in the divider. it would maintain flow velocity at low RPMs but allow the 2 sides to balance at higher revs.
IIRC the 300 EFI manifold has a divider in the plenum with a notch to allow some bleed from side to side. Very similar in concept and effect to some dual plane carb manifolds with a notch in the divider. it would maintain flow velocity at low RPMs but allow the 2 sides to balance at higher revs.
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intakes
Hey 007,
Let's get back to your question. I had an Offy Duel Port on a Ford 2.3 Powerd CJ3B many years ago, so I know what your talking about. The Duel Port is like a single plane except the runners are divided horizontaly. This divition is caried back to the carb where the carb primaries and secondaries are separated. The primaries feed the upper half (Port) of the intake runner and the secondaries feed the lower half.
The idea was to promote high speed flow in the upper port (for torque and MPG) and still have the lower for upper end HP when the secondaries opened up.
My little 2.3 was happy with it, and it never acted over carbed even with the 390 Holley on a 140 c.i. motor.
I hope this helps.
John
Let's get back to your question. I had an Offy Duel Port on a Ford 2.3 Powerd CJ3B many years ago, so I know what your talking about. The Duel Port is like a single plane except the runners are divided horizontaly. This divition is caried back to the carb where the carb primaries and secondaries are separated. The primaries feed the upper half (Port) of the intake runner and the secondaries feed the lower half.
The idea was to promote high speed flow in the upper port (for torque and MPG) and still have the lower for upper end HP when the secondaries opened up.
My little 2.3 was happy with it, and it never acted over carbed even with the 390 Holley on a 140 c.i. motor.
I hope this helps.
John
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Joined: May 2001
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From: N. MN
intakes
My friend has the single plane manifold on his 300, and I have the dual port manifold on mine. Mine has better low end than his does. We are running Offy 4bbl intakes, Dynomax 3 on 3 headers, Edelbrock 600cfm carbs, his is bored .060 shaved .060, Blue racer cam. Mine is shaved .035, with a Crane Cam.
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